Liquid crystal display device and method for fabricating the same

ABSTRACT

A method for fabricating a liquid crystal display device including a liquid crystal layer clamped between a first and second substrates. The method includes the steps of: forming a pixel electrode pattern on the first substrate; painting a resist film on the pixel electrode pattern; exposing and developing the resist film and forming a resist pattern having a shape on the pixel electrode pattern in which multiple branches extend outwardly from both sides of a main stem connecting among the multiple braches; and conducting an ashing process and a thermosetting process for the resist pattern. Liquid crystal molecules in the liquid crystal layer orient approximately in vertical to a surface of the liquid crystal layer in a non-driving state, and the liquid crystal molecules orient approximately in parallel to the surface of the liquid crystal layer in a driving state.

This is a divisional, of application Ser. No. 09/903,010, filed Jul. 11,2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to liquid crystal displaydevices, and more particularly to a liquid crystal display deviceapplying a vertical orientation mode.

The liquid crystal display device has been widely used for variousportable information processing apparatuses, especially, for laptopcomputers and cellular phones, as a display device that is minimized andrequires lower power consumption. Recently, a performance of the liquidcrystal display has been dramatically improved to be faster. Thus,recent technology of the liquid crystal display achieving a fasterresponse speed and a clearer contrast is realized to replace a CRTdisplay device of a desktop computer or a workstation computer.

However, such a conventional liquid crystal display is needed to improvethe response speed and the contrast in order to be especially applied toa flat display device of a desktop computer. Also, it is required torealize a wider angle of visibility to recognize information displayedon the conventional liquid crystal display device as much as a directview angle to a front of the conventional liquid crystal display device.

2. Description of the Related Art

Conventionally, as a practical liquid crystal device, a TN-type liquidcrystal display device that is normally in white mode has been widelyused. In the TN-type liquid crystal display device, an orientationdirection of liquid crystal molecules is changed depending on an appliedvoltage signal. A transmission light is controlled to turn ON or OFF bythe change of the orientation direction of the liquid crystal molecules.

However, in the TN-type liquid crystal display device, a ratio ofcontrast is limited because of an operation principle. Thus, it isdifficult to realize the wider view angle that is required for thedisplay device of the desktop computer.

On the contrary, the inventor of the present invention has alreadyproposed a liquid crystal display device are that liquid molecule in aliquid layer is oriented to an approximate vertical direction in advancebefore a driving voltage is applied, so called a vertical orientationliquid crystal display device.

A principle of a vertical orientation liquid crystal display device 10that is proposed by the inventor of the present invention, called an MVAtype, will now be described. FIG. 1A is a diagram showing a non-drivingstate in that the driving voltage is not applied to the liquid crystaldisplay device 10 and FIG. 1B is a diagram showing a driving state inthat the driving voltage is applied to the liquid crystal display device10.

Referring to FIG. 1A, a liquid crystal layer 12 is clamped between glasssubstrates 11A and 11B. The glass substrates 11A and 11B form a liquidpanel with the liquid crystal layer 12. Molecule orientation films (notshown) are formed on the glass substrates 11A and 11B. By effects of themolecule orientation film, in the state in which the driving voltage isnot applied, the liquid crystal molecules in the liquid crystal layer 12are oriented in the approximate vertical direction to the liquid crystallayer 12. In the non-driving state in FIG. 1A, because a deflectionangle of a deflection plate is not substantially changed, in a case inwhich a polarizer and an analyzer are provided on a top and a bottomsurfaces in a crossed Nicol state, an incident light beam, whichtransmits through the polarizer and enters the liquid crystal layer 12,is interrupted by the analyzer.

On the other hand, in the driving state in FIG. 1B, the liquid moleculesare tilted by influence of the applied electric field. Then, thedeflection direction of the deflection plate is changed. As a result,the incident light beam, which transmits through the polarizer andenters the liquid crystal layer 12, transmits through the analyzer.

Moreover, in the liquid crystal display device 10 in FIG. 1A and FIG.1B, during the transmission from the non-driving state to the drivingstate, in order to suppress a tilt direction of the liquid crystalmolecules and improve the response speed, extended projecting patterns13A and 13B are alternately formed on the glass substrates 11A and 11Bin parallel.

By forming the projection patterns 13A and 13B, the response speed ofthe liquid crystal display device 10 is improved and simultaneously aplurality of domains are formed in different directions of tilting theliquid crystal molecule in the liquid crystal layer 12. As a result, theview angle of the liquid crystal display device 10 is greatly improved.

FIG. 2 is a diagram showing an orientation state of the liquid crystalmolecules in vicinities of the projection patterns 13A and 13B in thedriving state in FIG. 1B.

Referring to FIG. 2, the liquid crystal molecules are tilted in thedriving state and an angle difference is about 180° between orientationdirections of the projections 13A and 13B. That is, the projections 13Aand 13B are twisted. In FIG. 2, a polarizer absorbent axis P and ananalyzer absorbent axis A are shown.

In liquid crystal display device 10 having the vertical orientation,while the tilted liquid crystal molecules are twisted up to 180°, theorientation of the liquid crystal molecules at one edge of theprojection 13A or 13B always corresponds to a direction of the polarizerabsorption axis P and the orientation at another edge of the projection13A or 13B always corresponds to a direction of the analyzer absorptionaxis A. When such the orientation of the liquid crystal moleculesoccurs, two dark lines shown in FIG. 2 appear along both edges of theprojection 13A or 13B. The two dark lines deteriorate transmittance of aliquid crystal panel and then also, the contrast of liquid crystaldisplay device 10 is deteriorated.

In addition, in the liquid crystal display device 10 shown in FIG. 1Aand FIG. 1B, a tilt direction is controlled in the vicinities of theprojections 13A and 13B but the tilt direction is not controlled inregions other than the vicinities. As a result, when a state of theliquid crystal display device 10 transits from the non-driving state inFIG. 1A to the driving state in FIG. 1B, the liquid crystal moleculesstart to be tilted in a given direction at the vicinities of theprojections 13A and 13B and then tilt of the liquid crystal molecules atthe vicinities propagate the liquid crystal molecules in the regionsother than the vicinities. Finally, all liquid crystal molecules aretilted in the given direction. However, the response speed of such tiltpropagation takes time. Thus, it is desired to improve the responsespeed. Especially, when a half tone is displayed by the tiltpropagation, the tilt direction of the liquid crystal molecules locatedfar from the projection patterns 13A and 13B is not defined since anelectric field applied to the liquid crystal molecules is weak.Consequently, the response speed tends to delay.

Also, in the conventional liquid crystal display device 10 shown in FIG.1A and FIG. 1B, the projection patterns 13A and 13B are required to beat least 1.2 μm height. However, when the projection patterns having a1.2 μm height are formed by resist, a retardation of the liquid crystallayer 12 is decreased at the projection patterns 13A and 13B. Also, thedecrease of the retardation degrades transmittance of the liquid crystallayer 12.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide liquidcrystal display devices in which the above-mentioned problems areeliminated.

A more specific object of the present invention is to provide a liquidcrystal display device that can realize a high contrast performance, ahigh response speed and a wider view angle.

The above objects of the present invention are achieved by a liquidcrystal display device comprising: a first substrate; a second substratefacing the first substrate; a liquid crystal layer sealed between thefirst substrate and the second substrate; a first electrode formed onthe first substrate; a second electrode formed on the second substrate;a first molecule orientation film formed on the first substrate so as tocover the first electrode; a second molecule orientation film formed onthe second substrate so as to cover the second electrode; a firstpolarizing plate provided outside of the first substrate; and a secondpolarizing plate provided outside of the second substrate in a crossedNicol state to the first polarizing plate, wherein: in a non-drivingstate in which a driving voltage is not applied between the firstelectrode and the second electrode, liquid crystal molecules areoriented in a vertical direction to the first substrate and the secondsubstrate by the first molecule orientation film and the second moleculeorientation film, respectively; on the first substrate, a structuralpattern is formed so as to extend in a first direction parallel to asurface of the liquid crystal layer and so as to form, in a drivingstate in which a driving voltage is applied between the first electrodeand the second electrode, an electric field periodically changing in asecond direction that is parallel to the liquid crystal layer andvertical to the first direction; and the liquid crystal moleculessubstantially tilt in the first direction in the driving state.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings, in which:

FIG. 1A is a diagram showing a non-driving state in that the drivingvoltage is not applied to the liquid crystal display device 10 and FIG.1B is a diagram showing a driving state in that the driving voltage isapplied to the liquid crystal display device 10;

FIG. 2 is a diagram showing an orientation state of the liquid crystalmolecules in vicinities of the projection patterns in the driving statein FIG. 1B;

FIG. 3A and FIG. 3B are diagrams for explaining a principle of thepresent invention;

FIG. 4 is a diagram for explaining a principle of the present invention;

FIG. 5 is a diagram showing experiment results of the liquid crystaldisplay device in FIG. 3A and FIG. 3B;

FIG. 6 is a schematic diagram showing a configuration of the liquidcrystal display device 30 according to a first embodiment of the presentinvention;

FIG. 7A is a sectional diagram of the liquid crystal display device andFIG. 7B is a diagram showing a magnified part of the TFT glasssubstrate;

FIG. 8 is a diagram showing a detail configuration of the pixelelectrode formed on the TFT glass substrate;

FIG. 9 is a diagram for explaining an operation of the liquid crystaldisplay device.

FIG. 10 is a diagram showing the principle of the second embodiment tothe present invention;

FIG. 11 is a diagram showing another principle as a base of theconfiguration in FIG. 10, according to the second embodiment of thepresent invention;

FIG. 12 is diagram showing another principle as a base of theconfiguration in FIG. 10, according to the second embodiment of thepresent invention;

FIG. 13 is diagram showing another principle as a base of theconfiguration in FIG. 10, according to the second embodiment of thepresent invention;

FIG. 14A through 14D are diagrams showing experiment results of theliquid crystal display device in FIG. 12 and FIG. 13;

FIG. 15 is a diagram showing another liquid crystal display device 40based on the principle previously described, according to the secondembodiment of the present invention;

FIG. 16 is a diagram showing a substrate of the liquid crystal displaydevice according to a third embodiment of the present invention;

FIG. 17 is a diagram for explaining a principle of a liquid crystaldisplay device according to the third embodiment of the presentinvention;

FIG. 18 is a diagram for explaining another principle of a liquidcrystal display device according to the third embodiment of the presentinvention;

FIG. 19 is a diagram for explaining another principle of a liquidcrystal display device according to the third embodiment of the presentinvention;

FIG. 20 is a diagram showing an operational characteristic of the liquidcrystal display device according to the third embodiment of the presentinvention;

FIG. 21 is a diagram of a liquid crystal display device according to thethird embodiment of the present invention;

FIG. 22 is a diagram showing a first variation of the liquid crystaldisplay device according to the third embodiment of the presentinvention;

FIG. 23 is a diagram showing a second variation of the liquid crystaldisplay device according to the third embodiment of the presentinvention;

FIG. 24 is a diagram showing an operational characteristic of the liquidcrystal display device according to the third embodiment of the presentinvention;

FIG. 25A and FIG. 25B are diagram for explaining a principle based onthe configuration in FIG. 4, according to the fourth embodiment of thepresent invention;

FIG. 26 is a diagram showing a configuration of a pixel electrode partof a liquid crystal display device according to the present invention;

FIG. 27 is a diagram of a liquid crystal display device 60A showing afirst variation of the configuration of the liquid crystal displaydevice 60 according to the fourth embodiment of the present invention;

FIG. 28 is a diagram showing a second variation of the configuration ofthe liquid crystal display device according to the fourth embodiment ofthe present invention;

FIG. 29 is a diagram showing a principle of a liquid crystal displaydevice according to a fifth embodiment of the present invention;

FIG. 30 is a diagram showing the configuration of the liquid crystaldisplay device according to the fifth embodiment of the presentinvention;

FIG. 31A is a diagram showing a change of a transmittance and a responsespeed in the liquid crystal display device in FIG. 30 and FIG. 31B is adiagram showing orientations of the liquid crystal molecules in theliquid crystal display device in FIG. 30;

FIG. 32 is a diagram showing a relationship between an achievedtransmittance and a required time in the liquid crystal display devicein FIG. 30, according to the fifth embodiment of the present invention;

FIG. 33 is a diagram showing a relationship between an achievedtransmittance and a required time in the liquid crystal display devicein FIG. 30, according to the fifth embodiment of the present invention;

FIG. 34 is a diagram showing a relationship between a transmittance anda gradation in a first variation and a second variation in FIG. 33,according to the fifth embodiment of the present invention;

FIG. 35A through FIG. 35C are diagrams showing various patterns used asthe pixel electrode, according to the fifth embodiment of the presentinvention;

FIG. 36A through FIG. 36T are diagrams for explaining a method forfabricating a liquid crystal display device according to a sixthembodiment of the present invention;

FIG. 37 is a diagram showing a variation of the liquid crystal displaydevice according to a sixth embodiment of the present invention;

FIG. 38A and FIG. 38B are diagrams showing a principle of a liquidcrystal display device according to a seventh embodiment of the presentinvention;

FIG. 39 is a diagram showing a photo mask used for fabricating theliquid crystal display device according to the seventh embodiment of thepresent invention;

FIG. 40 is diagrams showing a result of simulating an operation of theliquid crystal display device according to the seventh embodiment of thepresent invention;

FIG. 41A is a diagram showing a pattern variation of the liquid crystaldisplay according to the seventh embodiment of the present invention andFIG. 41B is a diagram showing another pattern variation of the liquidcrystal display according to the seventh embodiment of the presentinvention;

FIG. 42 is a diagram showing a liquid crystal display device accordingto an eighth embodiment of the present invention;

FIG. 43 is a diagram showing the directional pattern according to aneighth embodiment of the present invention;

FIG. 44 is a diagram showing a first variation of the liquid crystaldisplay device 100 in FIG. 42, according to the eighth embodiment of thepresent invention;

FIG. 45 is a diagram showing a second variation of the liquid crystaldisplay device in FIG. 42, according to the eighth embodiment of thepresent invention;

FIG. 46 is a diagram showing a third variation of the liquid crystaldisplay device in FIG. 44, according to the eighth embodiment of thepresent invention;

FIG. 47 is a diagram showing a fourth variation of the liquid crystaldisplay device 100 in FIG. 45, according to the eighth embodiment of thepresent invention;

FIG. 48 is a diagram showing a fifth variation of the directionalpattern according to the eighth embodiment of the present invention;

FIG. 49 shows diagrams of various directional patterns, instead of thedirectional pattern, according to the eighth embodiment of the presentinvention;

FIG. 50A and FIG. 50B are diagrams showing arrangement variations of thedirectional pattern according to the eighth embodiment of the presentinvention;

FIG. 51 is a diagram showing arrangement variations of the directionalpattern according to the eighth embodiment of the present invention;

FIG. 52 is a diagram showing arrangement variations of the directionalpattern according to the eighth embodiment of the present invention;

FIG. 53A is a sectional view diagram showing a liquid crystal displaydevice according to a ninth embodiment of the present invention and FIG.53B is a plan view diagram showing a liquid crystal display deviceaccording to the ninth embodiment of the present invention;

FIG. 54 is a diagram showing the orientation of the liquid crystalmolecules in the liquid crystal layer in the driving state of the liquidcrystal display device, according to the ninth embodiment of the presentinvention;

FIG. 55A through FIG. 55D are diagrams for explaining a method forfabricating the liquid crystal display device shown in FIG. 53A and FIG.53B, according to the ninth embodiment of the present invention;

FIG. 56 is a diagram showing a first variation of the liquid crystaldisplay device according to the ninth embodiment of the presentinvention;

FIG. 57 is a diagram showing a second variation of the liquid crystaldisplay device according to the ninth embodiment of the presentinvention;

FIG. 58 is a diagram showing a third variation of the liquid crystaldisplay device according to the ninth embodiment of the presentinvention; and

FIG. 59 is a diagram showing a fourth variation of the liquid crystaldisplay device according to the ninth embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3A and FIG. 3B are diagrams for explaining a principle of thepresent invention.

Referring FIG. 3A, a liquid crystal display device 20 according to thepresent invention, includes a pair of the glass substrates 21A and 21B.Electrode layers 23A and 23B are formed on the glass substrates 21A and21B. In addition, micro structural patterns 24 are formed on the glasssubstrate 21A so as to transform a electric field pattern formed betweenthe electrode layers 23A and 23B on a surface of the electrode layer23A. Moreover, a molecule orientation film 25A is formed so as to coverthe micro structural patterns 24 on the surface of the electrode layer23A. On the other hand, on the glass substrate 21B, a moleculeorientation film 25B is formed so as to cover the electrode layer 23B.The molecule orientation films 25A and 25B contact the liquid layer 22and the liquid molecules 22A in the liquid layer 22 are regulated in anapproximately vertical direction to the surface of the liquid layer 22in the non driving state in which an electric field is not applied tothe electrode layers 23A and 23B.

Furthermore, a polarizer 26A having a first light absorbent axis isformed on a principal plane at bottom of the glass substrate 21A and ananalyzer 26B having a second light absorbent axis is formed on aprincipal plane at bottom of the glass substrate 21B.

The micro structural patterns 24 form a plurality of insulating orconducting micro projection patterns that are alternately formed andextend in parallel on the electrode layer 23A. The micro structuralpatterns 24 locally transform an electric field in the liquid layer 22.For example, as shown in FIG. 4, the micro structural patterns 24 can bemicro concave patterns such as cutout patterns that are formed so as toextend in parallel. In a case in which the micro structural patterns 24are formed by micro convex patterns, the convex patterns are preferablyformed by s transparent material so that a light beam entered the liquidcrystal display device 20 transmits through.

In FIG. 3B, orientations of the liquid crystal molecule 22A at thesurface of the glass substrate 21A is shown in the driving state of theliquid crystal display device 20 in which the driving voltage is appliedto the electrode layers 23A and 23B.

Referring to FIG. 3B, the electric field in the liquid crystal displaydevice 20 according to the present invention is locally transformed bythe micro structural pattern 24 in the driving state. Then, the liquidcrystal molecules 22A fall down and orients in the extended direction.Therefore, in a case in which the polarizer 26A and the analyzer 26B arearranged so as to have an absorbent axis P and a absorbent axis A asshown in FIG. 3B, the dark lines described in FIG. 2 do not occur.

In the liquid crystal display device 20 according to the presentinvention, when the driving voltage is applied to between the electrodelayer 23A and 23B and a driving electric field is formed in the liquidcrystal layer 22, each liquid crystal molecule falls down in theextended direction of the micro structural patterns 24 in response tothe driving electric field transformed by the micro structural patterns24. Differently from the conventional liquid crystal display device inFIG. 1A and FIG. 1B, when the liquid crystal molecules fall down,response speed is greatly improved since the tilt of the liquid crystalmolecules does not have to propagate from vicinity regions of the convexpatterns 13A and 13B to other regions.

In addition to these advantages, in the liquid crystal display device 20as shown in FIG. 3B, the orientation direction of each liquid crystalmolecule 22A is substantially regulated in the extended direction of themicro structural patterns 24 in the driving state. Since tilted liquidcrystal molecules 22A interact, a twist angle of each liquid crystal 22Ais not changed in the liquid crystal layer 22. Therefore, it is possibleto display at a higher quality of contrast.

When the driving voltage is applied to between the electrode layers 23Aand 23B, the micro structural patterns 24A almost evenly form anelectric field distribution in a first direction corresponding to theextended direction of the micro structural patterns 24A and periodicallyform the electric field distribution in a second direction beingvertical to the first direction, in the liquid crystal layer 22.

FIG. 5 is a diagram showing experiment results of the liquid crystaldisplay device in FIG. 3A and FIG. 3B. In FIG. 5, when ratio of a widthto an interval of the micro structural pattern 24 is variously changed.In the experiment in FIG. 5, when a thickness of the liquid crystallayer 22 is set to 3.5 μm and the interval between adjacent microstructural patterns 24 is fixed to 3 μm, the width of each microstructural pattern 24 is variously changed. The electrode layers 23A and23B are uniformly formed by the ITO films.

Referring to FIG. 5, especially, when the width and the interval of themicro structural pattern 24 are 3 μm, that is, the ratio of the width tothe interval is 1 to 1, the transmittance close to 30% can be obtained,which transmittance greatly exceeds more than the conventional liquidcrystal display device 10 in FIG. 1 and is equal to the transmittance ofthe TN mode liquid crystal display device. Consequently, in the liquidcrystal display device 20, the problem of occurrences of the dark linesdescribed in FIG. 2 is solved. In FIG. 5, in the conventional liquidcrystal display device 10 without micro structural patterns 24, thethickness of the liquid crystal layer is set to 3.5 μm and the intervalbetween the projection pattern 13A and 13B is set to 30 μm.

[First Embodiment]

FIG. 6 is a schematic diagram showing a configuration of a liquidcrystal display device 30 according to a first embodiment of the presentinvention.

Referring to FIG. 6, the liquid crystal display device 30 is an activematrix operation type liquid crystal display device. The liquid crystaldisplay device 30 includes a TFT glass substrate 31A carrying aplurality of thin film transistors (TFTs) and a plurality of transparentpixel electrodes cooperating with the TFTs, corresponding to theelectrode layer 23A shown in FIG. 3A or FIG. 4, and a facing glasssubstrate 31B providing above the TFT glass substrate 31A and carryingfacing electrodes corresponding to the electrode layer 23B shown in FIG.3A or FIG. 4 where a liquid crystal layer 31 is sealed between the TFTglass substrate 31A and the facing glass substrate 31B by a seal member31C. In the liquid crystal display device 30 in FIG. 6, the transparentpixel electrode is selected and operated through a TFT correspondingthereto and then the orientation of the liquid crystal is selectivelychanged by corresponding to a selected transparent pixel electrode inthe liquid crystal layer 31. Moreover, a polarizer 31 a and an analyzer31 b are arranged in the crossed Nicol state outside of the TFT glasssubstrate 31A and the facing glass substrate 31B. Also, moleculeorientation films corresponding to the molecule orientations films 25Aand 25B in FIG. 3A or FIG. 4A are formed so as to be adjacent to theliquid crystal layer 31 inside of the TFT glass substrate 31A and thefacing glass substrate 31B. In the non-driving state, the orientationdirection of the liquid crystal molecules is controlled to beapproximately vertical to a surface of the liquid crystal layer 31.

A liquid crystal having a negative inductive factor anisotropy providedby Merck corporation can be used for the liquid crystal layer 31 and avertical orientation film provided by JSR corporation can be used forthe molecule orientation film. As a typical example, the TFT glasssubstrate 31A and the facing glass substrate 31B are configured by usingan appropriate spacer so that a thickness of the liquid crystal layer 31is approximate 4 μm.

FIG. 7A is a sectional diagram of the liquid crystal display device 30and FIG. 7B is a diagram showing a magnified part of the TFT glasssubstrate 31A.

Referring to FIG. 7A, each pixel electrode 34 is electrically connectedto a TFT 31T (not shown) and is formed on the TFT glass substrate 31A,which is a bottom side of a TFT substrate. The pixel electrodes 34 arecovered with a vertical molecule film 35. Similarly, each facingelectrode 36 is uniformly formed on the facing glass substrate 31B,which is a top side of the TFT substrate and the facing electrodes arecovered with another molecule orientation film 37. The liquid crystallayer 31 is clamped between the TFT glass substrate 31A and facing glasssubstrate 31B in an adjacent state by the molecule orientation films 35and 37.

Referring to FIG. 7B, on the TFT glass substrate 31A, a plurality of padelectrodes 33A supplying scan signals and a plurality of scan electrodes33 extended from the pad electrodes 33A, and a plurality of padelectrodes 32A supplying video signals and a plurality of signalelectrodes 32 extended from the pad electrodes 32A are formed so that anextended direction of the scan electrodes 33 and that of the signalelectrodes 32 cross each other at approximately a right angle. At eachcross point of the scan electrodes 33 and the signal electrodes 32, theTFT 31T in FIG. 8 is formed. Moreover, on the TFT glass substrate 31A,the pixel electrode 34, which is transparent, corresponding to each TFT31T is formed. Each TFT 31T is selected by the scan signal on each scanelectrode 33 corresponding to the TFT 31T. Then, each pixel electrode 34such as an ITO is operated by a video signal on the signal electrode 32corresponding to a selected TFT 31T.

A display of the liquid crystal display device 30 is turned “black” byeffects of the polarizer 31 a and the analyzer 31 b since the liquidcrystal molecules are approximate vertically oriented to the surface ofthe liquid crystal layer 31 in the non-driving state in which thedriving voltage is not applied to the transparent pixel electrodes 34.And, the display of the liquid crystal display device 30 is turned“white” since the liquid crystal molecules are approximate horizontallyoriented in the driving state in which the driving voltage is applied tothe transparent pixel electrodes 34.

In FIG. 7A, one or a plurality of phase compensation films can beprovided between the TFT glass substrate 31A and the polarizer 31 a,and/or between the facing glass substrate 31B and the analyzer 31 b. Forexample, the phase compensation films can be an optically uniaxial phasecompensation film where refractive indexes nx and ny inside of theliquid crystal layer 31 are greater than a refractive index nz of alight wave in a proceeding direction.

FIG. 8 is a diagram showing a detailed configuration of the pixelelectrode 34 formed on the TFT glass substrate 31A.

Referring to FIG. 8, each signal electrode 32 and each scan electrode 33cross each other on the TFT glass substrate 31A and the TFT 31T and thepixel electrode 34 are formed at a cross point of each signal electrode32 and each scan electrode 33. Also, in FIG. 8, an auxiliary capacitanceelectrode Cs is formed in parallel to the scan electrode 33.

In FIG. 8, the pixel electrode 34 is shown by a dotted area and issectioned into regions A, B, C and D. On each of the regions A, B, C andD, a plurality of micro-cutout patterns 34A, which are shown in whiteand correspond to the configuration described in FIG. 4, are extendedand formed in parallel.

In a typical example, the micro-cutout pattern 34 is 3 μm to 13 μm inwidth. For example, the micro-cutout pattern 34 is formed at intervalsof approximate 3 μm. The micro-cutout pattern 34 in each of the regionsA, B, C and D is formed so that one extended direction of themicro-cutout pattern 34 in one region crosses with another extendeddirection of the micro-cutout pattern 34 in another region. In thiscase, in any one of regions A, B, C and D, the extended direction of themicro-cutout pattern 34 is set so as to slantingly cross with the lightabsorption axis A of the polarizer 31 a shown in FIG. 6 and the lightabsorption axis P of the analyzer 31 b shown in FIG. 6.

In the liquid crystal display device 30, when the TFT 31T is activatedand the driving voltage is applied to the pixel electrode 34, the liquidcrystal molecules in the liquid crystal layer 31 fall down in theextended direction of the micro-cutout pattern 34 as shown in FIG. 8.However, each direction where the liquid crystal molecules fall down inthe regions A, B, C and D is different. Therefore, the liquid crystaldisplay device 30 shows a characteristic of a wider visibility angle.

In the driving state of the liquid crystal display device 30 accordingto the present invention, the liquid crystal molecules are influenced bythe electrode field formed by the micro-cutout pattern 34 andperiodically changing in a direction of vertically crossing to theextended direction of the pixel electrode 34. Then, the liquid crystalmolecules fall down in the extended direction of the micro-cutoutpattern 34 without being regulated by a direction where other liquidcrystal molecules are tilted. Thus, a change from a vertical orientationstate to a horizontal orientation state of the liquid crystal moleculesor from the horizontal orientation state to the vertical orientation isspeedy. The transition from the non-driving state to the driving stateor from the driving state to the non-driving state is conducted at ahigher speed. The transition to a half tone state is also conducted at ahigher speed. For example, when the liquid crystal layer 31 is 4 μm inthickness and the micro-cutout pattern 34A is 3 μm in width andinterval, the transition from the non-driving state (black) to a halftone (¼ gradation) is completed in 70 msec; that is 20 msec shorter thana conventional transition. Also, the transition from black to white iscompleted in 17 msec; that is 2 msec shorter than the conventionaltransition.

Furthermore, according to the configuration of FIG. 8, the orientationdirection of the liquid crystal molecules is regulated in the drivingstate. Therefore, the twist angle is not changed by interactions withother liquid crystal molecules and then it is possible to realize anuniformly high quality display.

In the liquid crystal display device 30 including a plurality of domainsA, B, C and D that have different orientations in a single pixelelectrode 34 as shown in FIG. 8, an orientation direction of the liquidcrystal molecules as shown in FIG. 9 changes up to approximate 90° atone border between the domain A and the domain B adjacent to the domainA and at another border between the domain C and the domain D adjacentto the domain C. However, two dark lines do not appear along both edgesof a projection pattern as the conventional liquid crystal displaydevice 30. Therefore, the transmittance in the driving state can begreatly improved. In addition, the view angle can be greatly improved byforming domain A, B, C and D, so as to realize a 160° view angle in avertical direction and a horizontal direction. In details, thetransmittance is improved from 4.8% of the conventional liquid crystaldisplay device to 5.6% that is 20% up.

In the configuration in FIG. 8, the dark line appears at the borderbetween the domain A and the domain C and at the border between thedomain B and the domain D. However, since these border s are coveredwith a conductive pattern connected to the auxiliary capacitanceelectrode Cs, the dark line does not affect the display of the liquidcrystal display device 30.

In the liquid crystal display device 30 in the first embodiment, on thepixel electrode 34 instead of the micro-cutout pattern 34A, themicro-projection pattern can be similarly formed by an insulatingmaterial or a conducting material. In this case, for example, as aninsulating material, a resist pattern such as a positive resist PC 403that is a product of JSR corporation or the like can be used and anapproximate 0.4 μm thickness is preferable. In a case in which themicro-cutout pattern 34A is made up of the insulating material, it isrecognized that the transmittance is further improved up to 6.2%. In acase in which micro-cutout pattern 34A is made up of the insulatingmaterial, a sectional form of the liquid crystal display device 30 issimilar to that of the liquid crystal display device 20 described inFIG. 3A.

Moreover, in the liquid crystal display device 30 in the firstembodiment, instead of the micro-cutout pattern 34A, another patternsimilar to the micro-cutout pattern 34A can be formed by anothertransparent conducting material similar to the pixel electrode 34. Inthis case, in a previous stage of forming the pixel electrode 34, whenthe TFT 31T is formed, a SiN film used as an insulating protection filmfor the TFT 31T is patterned and a micro pattern corresponding to themicro-cutout pattern 34A is formed in the pixel electrode 34.Furthermore, an ITO film forming the pixel electrode 34 is layered onthe patterned SiN film, so that a conductive micro-cutout pattern 34Acan be formed. In this case, an approximate 5.8% of transmittance can beobtained.

Furthermore, another micro-cutout pattern similar to the micro-cutoutpattern 34A can be provided while another micro-cutout patterncorresponds to the pixel electrode 34 on the facing glass substrate 31B.

[Second Embodiment]

Next, another liquid crystal display device in that a response speed ofa liquid crystal display device 20 or 30 is improved will now bedescribed in a second embodiment of the present invention.

A principle of the second embodiment of the present invention will nowbe described with reference to FIG. 10.

FIG. 10 is a diagram showing the principle of the second embodiment ofthe present invention. In FIG. 10, the previous configuration shown inFIG. 3A and FIG. 3B is enhanced to a configuration shown in FIG. 10 andelements that are the same as the ones in previous figures are indicatedby the same reference numerals and the explanation thereof will beomitted.

In a liquid crystal display device 20 shown in FIG. 3A and FIG. 3B, whenthe driving voltage is applied to between the electrode layers 23A and23B, a direction where the liquid crystal molecules 22A fall down isregulated in an extended direction of the micro structural pattern 24.However, the liquid crystal molecules 22A still have freedom to falldown in one extended direction or an opposite 180° extended direction.Thus, it takes time to determine one of two directions in which theliquid crystal molecules 22A fall down at an initial state of atransition process.

Accordingly, in the second embodiment, as shown in FIG. 1 in the liquidcrystal display device 20 in FIG. 3A, the liquid crystal display device20A is formed so that other rough projection patterns 27A and 27B havinga greater pitch and a larger width are formed in another extendeddirection different from the extended direction of the micro structuralpattern 24. FIG. 10, other features of the liquid crystal display device20A are the same as the previous liquid crystal display devices 20 and30 and the explanation thereof will be omitted.

Referring to FIG. 10, the rough projection pattern 27A is formed on thesubstrate 21A and the rough projection pattern 27B is formed on thesubstrate 21B. The rough projection patterns 27A and 27B regulate adirection in which the liquid crystal molecules 22A fall down to theextended direction of the micro structural pattern 24 when the drivingvoltage is applied to the electrode layers 23A and 23B. The roughprojection patterns 27A and 27B typically correspond to the projectionpatterns 13A and 13B of the conventional liquid crystal display device10 and realize the same effect as the projection patterns 13A and 13B.That is, the configuration in FIG. 10 is a configuration in that theprojection patterns 13A and 13B in FIG. 1A are formed in a configurationincluding the micro structural pattern 24 in FIG. 3A. In theconfiguration in FIG. 10, the extended direction of the micro structuralpattern 24 vertically crosses the extended direction of the roughprojection patterns 27A and 27B. Similarly to the configuration in FIG.3A, FIG. 3B or FIG. 4, the extended direction of the micro structuralpattern 24 are provided so as to obliquely cross a polarizer absorptionaxis P of a polarizer 26A or an analyzer absorption axis A of ananalyzer 26B.

FIG. 11 is a diagram showing another principle as a base of theconfiguration in FIG. 10, according to the second embodiment of thepresent invention. In the configuration in FIG. 11, the extendeddirection of the micro-cutout projection 24 is changed at both sides ofthe rough projection pattern 27A on the substrate 21A and then the widerview angle is realized. In the configuration in FIG. 11, the extendeddirection of the micro structural pattern 24 obliquely crosses theextended direction of the projection pattern 27A or 27B. Thus, thepolarizer absorption axis P of the polarizer 26A and the analyzerabsorption axis A of the analyzer 26B horizontally or vertically crossthe extended directions the rough projection patterns 27A and 27B,respectively.

As described above, by combining projecting patterns 13A and 13B withthe micro structural pattern 24 according to the present invention, in acase of a transition of the liquid crystal display device 20A from thenon-driving state to the driving state, the change of orientation of theliquid crystal molecules is accelerated and then the response speed ofthe liquid crystal display device 20A is improved.

FIG. 12 and FIG. 13 are diagrams showing another principle as a base ofthe configuration in FIG. 10, according to the second embodiment of thepresent invention. FIG. 12 and FIG. 13 show test pattern configurationsused in an experiment in that the inventors of the present inventionobtained optimum configuration parameters for the micro structuralpattern 24 and the rough projection patterns 27A and 27B. In FIG. 12,the rough projection pattern 27A forms a lattice shape on the substrate21A and also the rough projection pattern 27B similarly forms a latticeshape while the rough projection pattern 27B is displaced against therough projection pattern 27A. On the contrary, in FIG. 13, differentlyfrom the configuration in FIG. 12, the micro structural pattern 24 onthe substrate 21A is not formed right under the rough projection pattern27A on the substrate 21B. A region formed by the lattice shape of therough projection pattern 27B is further divided into four domains by thelattice shape of the rough projection pattern 27A and the microstructural pattern 24 is formed in a different orientation in eachdomain.

FIGS. 14A, 14B, 14C and 14D show results of the experiment by theinventors to evaluate a transmittance in the test pattern configurationsshown in FIG. 12 and FIG. 13.

In a liquid crystal display device used in the experiment, the microstructural pattern 24 is 3 μm in thickness and is arranged at intervalsof 3 μm in each domain in FIG. 12 or FIG. 13 so as to be the same as theprevious embodiments. Moreover, in the experiment, either one of thelattice shaped rough projection patterns 27A and 27B is formed atvarious intervals and various heights by a resist pattern (LC200;Shipley Far East Corporation) 5 μm in width and then transmittancecharacteristics of a panel are visually evaluated in the driving state,that is, in a state in which the driving voltage 5V is applied tobetween the electrode layers 23A and 23B.

In the experiment, FIG. 14A shows a result in a case in which the roughprojection patterns 27A and 27B are formed in 0.95 μm height, FIG. 14Bshows a result in a case in which the rough projection patterns 27A and27B are formed in 0.75 μm height. FIG. 14C shows a result in a case inwhich the rough projection patterns 27A and 27B are formed in 0.5 μmheight. FIG. 14D shows a result in a case in which the rough projectionpatterns 27A and 27B are formed in 0.3 μm height. In FIGS. 14A, 14B, 14Cand 14D, a left side picture shows a case in which the orientationdirections of the polarizer 26A and the analyzer 26B correspond to theextended direction of the micro structural pattern 24, respectively,that is, shows a case in which the orientation directions of thepolarizer 26A and the analyzer 26B correspond to a tilt direction of theliquid crystal molecules 22A. On the other hand, a right side pictureshows a case in which the orientation directions of the polarizer 26Aand the analyzer 26B correspond to the extended directions of the roughprojection patterns 27A and 27B, respectively. In each diagram of FIGS.14A, 14B, 14C and 14D, two pictures on the right side correspond to thetest pattern configuration in FIG. 11 and two pictures on the left sidecorrespond to the test pattern in FIG. 12.

In each diagram in FIGS. 14A, 14B, 14C and 14D, the rough projectionpatterns 27A and 27B are arranged at intervals of 80 μm. As results ofFIGS. 14A, 14B, 14C and 14D, when the rough projection patterns 27A and27B have improper heights, the orientation of the liquid crystalmolecules is improperly determined along the micro structural pattern 24and then the dark line appears. Results of configurations in FIGS. 14A,14B, 14C and 14D show a preferable case in which the verticalorientation liquid crystal of Merck Corporation as a liquid crystallayer 22 is combined with the vertical molecule orientation films 25Aand 25B of JSR corporation and the liquid crystal layer 22 is 4 μm inthickness.

Regarding the results of FIGS. 14A, 14B, 14C and 14D, it is summarizedthat for the most preferable display quality, that is, the least defectdisplay quality, can be obtained in a case in which the rough projectionpatterns 27A and 27B are 0.75 μm or 0.5 μm in height as shown in FIG.14B or FIG. 14C. In addition, in each diagram shown in FIGS. 14A, 14B,14C and 14D, compared a configuration 20C in FIG. 11 with aconfiguration 20D in FIG. 12, the configuration 20C in FIG. 11 issuperior in display quality and approximate 4% higher in transmittance.

Moreover, first, the response speed of the configuration 20C in FIG. 12or the configuration 20D in FIG. 13, in which the transmittances aresuperior, is compared with that of the conventional liquid crystaldisplay device 10 described in FIG. 1A and FIG. 1B. In a case in whichthe interval of the projection pattern 13A or 13B in the conventionalliquid crystal display device 10 is set to 20 μm, the transition fromthe black state (non-driving state) to the white state (driving state)requires 104 msec. On the other hand, in the second embodiment, as aresult of combining the rough projection patterns 27A and 27B with themicro structural pattern 24, it can be recognized that the required timeis reduced to 71 msec and the response speed is greatly improved.Furthermore, in the liquid crystal display device 20C or 20D, in a casein which both intervals of the rough projection patterns 27A and 27B aredetermined as 30 μm, the transition from the black state to the whitestate requires 470 msec. Compared with a case in which the projectionpatterns 13A and 13B are arranged at the same interval in the liquidcrystal display device 10 in this case, the response time is 640 msec.Consequently, it is possible to greatly improve the response time in theconfiguration 20C or 20D.

FIG. 15 is a diagram showing another liquid crystal display device 40based on the principle previously described, according to the secondembodiment of the present invention. In FIG. 15, parts that are the sameas the ones in previous figures are indicated by the same referencenumerals and the explanation thereof will be omitted.

Referring to FIG. 15, the same pattern as that in FIG. 8 is formed asthe pixel electrode 34 on the glass substrate 31A of the liquid crystaldisplay device 40 and the pixel electrode 34 is shown by a dotted areasimilar to that in FIG. 8.

In the second embodiment, furthermore, lattice shaped rough projectpatterns 41A and 41B are repeated to form in the scan electrodedirection or the signal electrode direction at pitch intervals of thepixel electrode 34. Accordingly, in FIG. 15, the lattice shaped roughprojection patterns 41A and 41B are formed so as to fit to the domains Athrough D. On the other hand, similarly to the micro structural pattern24 in FIG. 12 or FIG. 13, the micro-cutout pattern 34A having a 3 μmwidth is formed at intervals of 3 μm at a 45° angle in each of domains Athrough D.

The rough projection patterns 41A and 41B are the same projection shapeas the projection patterns 13A and 13B of the conventional liquidcrystal display device 10. For example, when the liquid crystal displaydevice 40 is a liquid crystal display device in which a 15 inch displayof 1024×768 pixels is available and the rough projection pattern 41B isformed at intervals of 99 μm.

It should be noted that the rough projection patterns 41A and 41B arenot limited to a projection pattern made up of a resist or a conductingpattern but can be a concave pattern such as a cutout pattern or in anelectrode layer.

[Third Embodiment]

A liquid crystal display device in that the response speed of the liquidcrystal display device 20 or 30 is further improved will now bedescribed according to a third embodiment of the present invention.

First, a principle of the third embodiment will now be described withreference to FIG. 16.

FIG. 16 is a diagram showing a substrate of the liquid crystal displaydevice according to the third embodiment of the present invention. InFIG. 16, an example of a directional pattern 24A formed on the glasssubstrate 21A in FIG. 3A is shown.

Referring to FIG. 16, the directional pattern 24A is a triangleinsulating or conducting pattern. In a case in which the directionalpattern 24A instead of the micro structural pattern 24 periodicallyformed in the liquid crystal display device 20 in FIG. 3A is formed, anelectric field is locally transformed in the liquid crystal layer 22 asshown by contour lines in FIG. 16. Then, an electric field distributioninclined toward a pointed edge of the directional pattern 24A is formed.

Thus, if such a directional pattern 24A is formed in the liquid crystaldisplay device 20, instead of forming the micro structural pattern 24,the liquid crystal molecules 22A are tilted toward the pointed edge ofthe directional pattern 24A along an inclination formed by thedirectional pattern 24A when the driving voltage is applied to betweenthe electrode layers 23A and 23B.

A Table 1 shows a result of research into orientations of the liquidcrystal molecules in that the directional pattern 24A being triangularinstead of the micro structural pattern 24 is formed by resist patternsbeing of various shapes, that is, having different widths, differentlengths and different heights. In Table 1, a numerical value is shown ina μm unit.

TABLE 1 Orientation Degree Toward Axis Width Length Height Direction 310 0.3 ∘ 0.8 ∘ 15 0.3 ∘ 0.8 ∘ 20 0.3 ∘ 0.8 ⊚ 30 0.3 ⊚ 0.8 ⊚ 5 10 0.3 ∘0.8 ∘ 15 0.3 ∘ 0.8 ∘ 20 0.3 ∘ 0.8 ⊚ 30 0.3 ⊚ 0.8 ⊚ 7.5 10 0.3 Δ 0.8 Δ 150.3 Δ 0.8 ∘ 20 0.3 Δ 0.8 ∘ 30 0.3 ∘ 0.8 ⊚ 10 10 0.3 x 0.8 x 15 0.3 x 0.8Δ 20 0.3 x 0.8 Δ 30 0.3 Δ 0.8 ∘ 15 10 0.3 x 0.8 x 15 0.3 x 0.8 x 20 0.3x 0.8 x 30 0.3 Δ 0.8 Δ 20 10 0.3 x 0.8 x 15 0.3 x 0.8 x 20 0.3 x 0.8 x30 0.3 x 0.8 x

⊚: almost completely titled toward axis direction ∘: edge is tiltedtoward a slightly different direction;   but almost titled toward axisdirection Δ: tilted toward axis direction in half of region x: tiltedtoward axis direction in less than half of region

In the table 1, if a case, in which the orientation direction isdifferent only in a vicinity of each side of the directional pattern 24Abeing triangular, is included to a desired orientation state, it ispreferable that the width of the directional pattern 24A, that is, alength of a bottom side is set to be less than 10 μm. On the other hand,a preferable orientation is realized when the length of the directionalpattern 24A is a range of 10 μm through 30 μm. However, when the widthis 7.5 μm, the length is required to be more than 15 μm, and when thewidth is 10 μm, the length is required to be more than 30 μm. When thewidth of the directional pattern 24A exceeds 10 μm, a ratio of theliquid crystal molecules orienting toward other than the pointed edge ofthe directional pattern 24A, is increased.

Similarly to a previous case shown in

FIG. 4, the directional pattern 24A being triangular can also be aconcave pattern such as a cutout pattern in the electrode layer 23A.

Such a directional pattern is not limited to the directional pattern 24Abeing triangular shown in FIG. 16, but the top edge of the directionalpattern can be an edge of the directional pattern 24B which edge is cutout or an edge of the directional pattern 24C which edge is rounded.Moreover, as shown in FIG. 18, a directional pattern 24D in which twotriangles are rotated at 90 degree, respectively, and are joined to eachother, can realize the same effect as the directional pattern 24A. Asshown in FIG. 19, a directional pattern 24E in which two triangles arerotated at 180 degree, respectively, and are joined to each other tobecome rhombic shape, can also realize the same effect as thedirectional pattern 24A.

Particularly, in the directional pattern 24E being a rhombic shape inFIG. 19, the liquid crystal molecules tilt to a right side or a leftside against a center of the directional pattern 24E.

In the table 1, in a case in which the micro-cutout projection patternis made up of an electrode pattern (slit), instead of a convexstructured object, a tilted direction of the liquid crystal molecules isreversed. However, the micro-cutout projection pattern made up of anelectrode pattern has an almost equal effect as a convex structuredobject having 0.8 μm height since a strain of the electrode field isstronger toward the orientation degree of an axis direction.

Table 2 shows a result of research into orientations of the liquidcrystal molecules in that the directional pattern 24E being a rhombus isformed by resist patterns being of various shapes, that is, havingdifferent widths, different lengths and different heights. In Table 1, anumerical value is shown in a μm unit.

TABLE 2 Orientation Degree Toward Axis Width Length Height Direction 320 0.3 ∘ 0.8 ∘ 30 0.3 ∘ 0.8 ∘ 40 0.3 ∘ 0.8 ⊚ 60 0.3 ⊚ 0.8 ⊚ 5 20 0.3 ∘0.8 ∘ 30 0.3 ∘ 0.8 ∘ 40 0.3 ∘ 0.8 ⊚ 60 0.3 ⊚ 0.8 ⊚ 7.5 20 0.3 Δ 0.8 Δ 300.3 Δ 0.8 ∘ 40 0.3 ∘ 0.8 ∘ 60 0.3 ∘ 0.8 ⊚ 10 20 0.3 x 0.8 x 30 0.3 x 0.8Δ 40 0.3 Δ 0.8 Δ 60 0.3 ∘ 0.8 ∘ 15 20 0.3 x 0.8 x 30 0.3 x 0.8 x 40 0.3x 0.8 x 60 0.3 Δ 0.8 Δ 20 20 0.3 x 0.8 x 30 0.3 x 0.8 x 40 0.3 x 0.8 x60 0.3 x 0.8 x

⊚: almost completely tilted toward axis direction ∘: edge is tiltedtoward a slightly different direction;   but almost tilted toward axisdirection Δ: tilted toward axis direction in half of region x: tiltedtoward axis direction in less than half of region

Referring to Table 2, if a case, in which the orientation direction isdifferent only in a vicinity of each side of the directional pattern 24Ebeing a rhombus, is included to a desired orientation state, it ispreferable that the width of the directional pattern 24E, that is, alength of a bottom side is set to be less than 10 μm. On the other hand,a preferable orientation is realized when the length of the directionalpattern 24E is in a range of 20 μm through 60 μm.

Also, in Table 2, in a case in which the micro-cutout projection patternis made up of an electrode pattern (slit), instead of a convexstructured object, a tilted direction of the liquid crystal molecules isreversed. However, the micro-cutout projection pattern made up of anelectrode pattern has an almost equal effect a convex structured objecthaving 0.8 μm height since a strain of the electrode field is strongertoward the orientation degree of an axis direction.

FIG. 20 is a diagram showing an operational characteristic of the liquidcrystal display device according to the third embodiment of the presentinvention. In FIG. 20, a relationship between a transmittance and aresponse speed is shown in a case in which the liquid layer 22 of theliquid crystal display device 20 is 4 μm in thickness and thedirectional pattern 24E being a rhombus is formed by a resist patternbeing 70 μm in length, 10 μm in width and 0.4 μm in thickness. It shouldbe noted that the transmittance is defined 100% where the drivingvoltage is 5.4V in FIG. 20. Also, in the conventional liquid crystaldisplay device 10 in FIG. 1A and FIG. 1B, the projection patterns 13Aand 13B are formed at intervals of 10 μm by a resist pattern being 10 μmin width and 1.5 μm in height and other specifications for theconventional liquid crystal display device 10 are the same as those ofthe liquid crystal display device 20 used in the experiment. In FIG. 20,another relationship between the transmittance and the response speed inthis case of the liquid crystal display device 10 is shown for acomparison.

Referring to FIG. 20, in the liquid crystal display device 20 accordingto the third embodiment, under the same transmittance, the responsespeed is substantially shortened in a case including the half tonedisplay mode where the driving voltage less than 5.4V is applied.

FIG. 21 is a diagram of a liquid crystal display device according to thethird embodiment of the present invention. In a liquid crystal displaydevice 50 in FIG. 21, the directional pattern 24E being a rhombus inFIG. 19 is aligned on the pixel electrode 34 in the liquid crystaldisplay device 30 previously described in FIG. 6 through FIG. 8. In FIG.21, parts that are the same as the ones in previous figures areindicated by the same reference numerals and the explanation thereofwill be omitted.

Referring to FIG. 21, the pixel electrode 34 is sectioned into twosections of an upper domain and a lower domain. In the upper domain, themicro-cutout projection pattern 24E being a rhombus made up of a resistpattern or the like is repeated to form in a first direction crossing anextended direction of the scan electrode 33 at 45°. The micro-cutoutprojection pattern 24E is repeated to form in a second directioncrossing the first direction at 45°. When the driving voltage is appliedto the liquid crystal layer 31, the tilt direction of the liquid crystalmolecules in the liquid crystal layer 31 is regulated toward a top edgeof the directional pattern 24E by a local transformation of theelectrode field. As a result, as previously described in FIG. 20, theresponse speed of the liquid crystal display device 30 is greatlyimproved.

In the directional pattern 24E being a rhombus in FIG. 19 or FIG. 21 andfurthermore the directional patterns 24A through 24D being triangular inFIG. 16 through FIG. 18, both inclined sides can form steps as shown inFIG. 22. A step shaped pattern is easily formed. Therefore, a productionyield of the liquid crystal display device 30 can be improved.

[Fist Variation]

FIG. 23 is a diagram showing a first variation of the liquid crystaldisplay device according to the third embodiment of the presentinvention. In FIG. 23, a liquid crystal display device 50A as the firstvariation of the liquid crystal display device 50 is shown.

Referring to FIG. 23, in the first variation, the directional pattern24E, which a top edge is cut out, and formed as a triangle directionalpattern 24E′ on the pixel electrode 34 in FIG. 21 based on thedirectional pattern 24B in FIG. 17 that is a triangle on liquid crystaldisplay device 50A. As a result, a region 34F where no structuredpattern is formed is formed.

In the first variation of the third embodiment, the triangle directionalpattern 24E′ is formed only on areas where the orientation direction ofthe liquid crystal molecules is disordered. In this configuration, it ispossible to improve the transmittance and the response speed of theliquid crystal display device 50A.

[Second Variation]

Furthermore, in the third embodiment, in order to improve the responsespeed in the liquid crystal display device 30 shown in FIG. 6 throughFIG. 8, as a means for inducing local changes of the electric fieldsimilar to those of directional patterns 24A through 24E which are atriangle or a rhombus, an optical hardened composite having athree-dimensional liquid crystal skeleton may be introduced into in theliquid crystal layer 31 made up of a nematic liquid crystal. When theoptical composite is hardened and then an optical hardened material ismade, the liquid crystal skeleton is formed so as to incline to asubstrate 31A. Thus, it is possible to form an electric field incliningto the extended direction of the micro-cutout patterns 34A, which issimilar to the electric field described in FIG. 16. For example, whenthe optical hardened composite is used to regulate the orientationdirection in the conventional liquid crystal display device 10 shown inFIG. 1A and FIG. 1B, a large amount of optical hardened composite isrequired to be introduced. As a result, the orientation direction of theliquid crystal molecules is disordered. However, in the liquid crystaldisplay device 30 according to the present invention, the micro-cutoutpattern 34A regulates the orientation direction of the liquid crystalmolecules. Therefore, it is possible to preferably regulate orientationdirection by a slight amount of the optical hardened composite.

Accordingly in the second variation, in the liquid crystal displaydevice 30 previously described in the first embodiment, a liquid crystalmono achryrate monomer UCL-001-K1 of Dai Nippon Ink K.K. in addition tothe liquid crystal MJ96213 is additionally provided and then the monomeris hardened by emitting ultraviolet rays while applying 5.0V drivingvoltage so as to form a liquid crystal display device. In the opticalhardened material formed by a process described above, when the liquidcrystal display device 50A is in the non-driving state, thethree-dimensional liquid crystal skeleton orients in a directiondifferent from the orientation direction of the liquid crystalmolecules.

FIG. 24 is a diagram showing an operational characteristic of the liquidcrystal display device according to the third embodiment of the presentinvention. In FIG. 24, a relationship between a transmittance and aresponse speed is shown in a case in which the driving voltage isapplied. Similar to the case in FIG. 20, the conventional liquid crystaldisplay device 10 in FIG. 1A and FIG. 1B are compared in FIG. 24.

Referring to FIG. 24, in the liquid crystal display device according tothe second variation, the response speed is substantially shorter thanthat of the conventional liquid crystal display device. In particularly,the response speed in a half tone is greatly improved.

[Fourth Embodiment]

A liquid crystal display device similar to the liquid crystal displaydevice 40 previously described in FIG. 15, in which the micro structuralpattern 24 in FIG. 3A is combined with the projecting patterns 13A and13B, will now be described according to a fourth embodiment. In theliquid crystal display device according to the fourth embodiment, themicro structural pattern 24 is made up of a cutout pattern formed in theelectrode 23A as shown in FIG. 4. Also, the projecting pattern 13Aformed on the substrate 11A is made up of a cutout pattern formed in theelectrode layer 23A.

FIG. 25A and FIG. 25B are diagrams for explaining a principle based onthe configuration in FIG. 4, according to the fourth embodiment of thepresent invention. In FIG. 25A and FIG. 25B, for the sake ofconvenience, only the electrode layers 23A and 23B are shown. But thepolarizer 26A and the analyzer 26B and the molecule orientations 25A and25B are not shown. In FIG. 25A, it is shown that a wider gap 23G isperiodically repeated to form at greater intervals in the electrodelayer 23A while corresponding to the projection patterns 13A and 13B. InFIG. 25B, it is shown that a smaller gap 23 g is periodically repeatedto form at shorter intervals in the electrode layer 23A.

In FIG. 25A, when the wider gap 23G is formed in the electrode layer23A, an equipotential surface is locally transformed in the liquidcrystal layer 22 by effects of gap edges. As a result, even if in thenon-driving state in which the driving voltage is not applied betweenthe electrode layers 23A and 23B, a pre-tilt structure is obtained. Inthe pre-tilt structure, the liquid crystal molecules 22A in the liquidcrystal layer 22A tilt toward a center of electrode patterns configuringthe electrode layer 23A. Then, when the driving voltage is applied tobetween the electrode layers 23A and 23B in the liquid crystal layer 22where the pre-tilt structure is formed, the liquid crystal molecules 22Aquickly tilt in a pre-tilt direction.

On the other hand, as shown in FIG. 25B, in a case in which the gap 23g, which is repeated to form on the electrode layer 23A, is smaller anda repeat period of the gap 23 g is shorter, pre-tilt similar to that inFIG. 25A occurs in the non-driving state as shown at a left side of FIG.25B. However, in a case in which the driving voltage is applied betweenthe electrode layer 23A and the electrode layer 23B in the drivingstate, the liquid crystal molecules 22A, which tend to tilt in a rightdirection or a left direction, mutually interfere and then the liquidcrystal molecules 22A result in tilting in an extended direction of thegap 23 g, as shown at a right side of FIG. 25B.

In a state shown in FIG. 25A, when the driving voltage is applied, theliquid crystal molecules 22A is regulated to tilt at the right side orthe left side by the pre-tilt of the liquid crystal molecules 22A.However, tilted liquid crystal molecules 22A can not be regulated toarrange in a single direction. On the contrarily, if a configurationshown in FIG. 25B is combined with a configuration shown in FIG. 25A, itis possible to control an orientation of tilted liquid crystal molecules22A to orient in a specific direction when the liquid crystal molecules22A tilt to the right side or the left side. That is, in the secondembodiment of the present invention previously described in FIG. 10, acutout pattern formed in the electrode layer 23A is used, instead of therough projection pattern 27A, and also a micro-cutout pattern formed inthe electrode layer 23A is used, instead of the micro structural pattern24.

FIG. 26 is a diagram showing a configuration of a pixel electrode partof a liquid crystal display device 60 according to the presentinvention. In FIG. 26, elements that are the same as the ones inprevious figures are indicated by the same reference numerals and theexplanation thereof will be omitted.

Referring to FIG. 26, a configuration of the liquid crystal displaydevice 60 is similar to that of the liquid crystal display device 30previously described in FIG. 6 and FIG. 7, but a pixel electrode 61 isused, instead of using the pixel electrode 34.

The glass substrate 31B, a projection pattern 61A corresponding to theprojection pattern 13B previously described in FIG. 1A and FIG. 1B,which is made up of a resist pattern typically having 3 μm through 35 μmin width and 1.2 μm through 1.6 μm in height, is repeated to form whilethe projection pattern 61A is bent at a right angle in zigzag. Also, inthe pixel electrode 61, a cutout pattern 61B having a zigzag shapecorresponding to the projection pattern 61A is formed with a 4 μmthrough 15 μm width at an intermediate between the projection patternsneighboring each other. Moreover, in the configuration in FIG. 26, amicro-cutout pattern 61C, which is 2 μm through 5 μm in width butpreferably approximately 3 μm in width, is repeated to form at pitchintervals of the width, that is, 2 μm through 5 μm but preferablyapproximate 3 μm, in the pixel electrode 61 so as to laterally extendfrom the cutout pattern 61B. As a result of forming the micro-cutoutpattern 61C, the pixel electrode 61 becomes a set of pectinate patterns61D having long and slender teeth. In the configuration in FIG. 26, thepixel electrode 61 includes a first domain where the projection pattern61A extends from upper right to lower left and a second domain where theprojection pattern 61A extends from upper left to lower right.Accordingly, an extended direction of the pectinate pattern 61D in thefirst domain is different from that in the second domain. That is, theextended direction of the pectinate pattern 61D in the first domainvertically crosses the extended direction of the pectinate pattern 61Din the second domain.

The set of the pectinate patterns 61D is needed to form a single pixelelectrode 61. Thus, the pectinate patterns 61D are mutually connected atedge sides 61 m of the pixel electrode 61 and right under the projectionpattern 61A of the facing glass substrate 31B in FIG. 6.

Furthermore, in the liquid crystal display device 60 in FIG. 26, atransparent or opaque common electrode pattern 61E′ is extended alongthe cutout pattern 61B. The transparent or opaque common electrodepattern 61E′ is directly formed on the glass substrate 31A, that is, isformed across an insulating film under the pixel electrode 61 and thenforms the auxiliary capacitance electrode Cs. The common electrodepatterns 61E and 61E′ are electrically connected. In this case, thetransparent common electrode pattern 61E′ shows parts obliquelyextending in the pixels from the common electrode pattern 61E. Thetransparent common electrode pattern 61E′ maintains the same electricpotential as a facing electrode on the facing glass substrate 31B. As aresult, a molecule orientation effect by the wider cutout pattern 61Bcan be reinforced. In this case, the common electrode pattern 61E′crosses the signal electrode 32 in FIG. 26 through FIG. 28. Butpractically, it is preferable to cut off the common electrode pattern61E′ before crossing the signal electrode 32. If the common electrodepattern 61E′ is formed in the extended direction, the common electrodepattern 61E′ may cause a short with the signal electrode 32. Even in acase in which the common electrode pattern 61E′ is cut off before thesignal electrode 32, an excellent effect can be obtained.

Also, in the liquid crystal display device 60 in FIG. 26, thetransparent or opaque common electrode pattern 61E′ forming theauxiliary capacitance electrode Cs passes through a region marked by acircle line in FIG. 26 and extends in a direction extending toward thescan electrodes 33. Then, the orientation of the liquid crystalmolecules is stabilized in the region marked by the round line.

As previously described in FIG. 25A and FIG. 25B, in the configurationof the liquid crystal display device 60, the tilt direction of theliquid crystal molecules in the liquid crystal layer is determined bythe common electrode pattern 61E, which pattern 61E is formed whilecorresponding to the cutout pattern 61B. In addition, the tilt directionof the liquid crystal molecules is regulated by the micro-cutout pattern61C and the pectinate pattern 61D. As a result, in the liquid crystaldisplay device 60, the response speed is improved and the displayquality is improved. Specificallfy, stability of the orientationdirection of the liquid crystal molecules is improved. Therefore, it ispossible to prevent a development of an image to display from remainingin a previous image, even if the image displayed is rapidly changed.

In the region marked by the circle line in FIG. 26, the micro-cutoutpattern 61C extends across the region right under the projection pattern61A on the facing glass substrate 31B. In this configuration, it can berealized to regulate the orientation of the liquid crystal molecules.Also, the projection pattern 61A can be a cutout pattern formed on afacing electrode.

[First Variation]

FIG. 27 is a diagram of a liquid crystal display device 60A showing afirst variation of the configuration of the liquid crystal displaydevice 60 according to the fourth embodiment of the present invention.

Referring to FIG. 27, in the first variation, the micro-cutout pattern61C in FIG. 26 is replaced with a cutout pattern 61C′ that is the sameas the directional pattern 24A being triangular previously describe inFIG. 16. As previously described, since the directional pattern inducesthe electric field distribution having a direction, in the liquidcrystal display device 60, the molecule orientation effect can bereinforced by the projection pattern 61A, the cutout pattern 61B and thecommon electrode patterns 61E. As a result, in the liquid crystaldisplay device 61A, the response speed is more improved.

[Second Variation]

FIG. 28 is a diagram showing a second variation of the configuration ofthe liquid crystal display device 60 according to the fourth embodimentof the present invention.

As shown in FIG. 28, in the liquid crystal display device 60 in FIG. 26,a pectinate pattern 61A similar to the pectinate pattern 61D can beformed on the facing glass substrate 31B so as to be provided betweenthe facing electrode 36 and the liquid crystal layer or between thefacing substrate 31B and the facing electrode 36. In addition, in a casein which the orientation of the liquid crystal molecules is regulatedenough by the projection pattern 61 or 61A′ and the cutout pattern 61B,as shown in FIG. 28, the micro-cutout pattern 61C formed in the pixelelectrode 61 is not formed in a region A, so that an uniform electrodeis formed. Moreover, instead of the projection pattern 61A or 61A′, acutout pattern, which corresponds to the facing electrode 36 of theglass substrate 31B.

[Fifth Embodiment]

Next, a fifth embodiment, in which the operational characteristic of theliquid crystal display device 60A in FIG. 27 is further improved, willnow be described.

In the liquid crystal display device 60A in FIG. 27, a high-speedresponse can be realized by forming the micro-cutout pattern 61C being ataper shape in the pixel electrode 61. However, in the configuration ofthe liquid crystal display device 60A in FIG. 27, the micro-cutoutpattern 61C is required to form on substantially an entire surface otherthan areas where the cutout pattern 61B is formed in the pixel electrode51. That is, a highly accurate photolithography process is required toform the micro-cutout pattern 61C being a taper shape and a yield of theliquid crystal display device 60A is deteriorated.

To eliminate the above problem, the inventor of the present inventionexamined the display characteristic. The inventor formed a pixelelectrode structure 71 laterally and periodically extending a pectinateITO (In₂O₃·SnO₂) pattern 71B from a banded ITO pattern 71A shown in FIG.30 and then variously changed a length B of the pectinate ITO pattern71B and a width A of the banded ITO pattern 71A in the liquid crystaldisplay device 70 having the pixel electrode structure 71.

FIG. 30 is a diagram showing the configuration of the liquid crystaldisplay device 70 according to the fifth embodiment of the presentinvention. In FIG. 30, specifically, a configuration of the pixelelectrode structure 71 is shown.

Referring to FIG. 30, the pixel electrode structure 71 includes aplurality of banded ITO patterns 71A. Each of the banded ITO patterns71A has the pectinate ITO pattern 71B. Also, each of the plurality ofbanded ITO patterns 71 has the width B shown in FIG. 29 on one side andis mutually spaced by a gap G corresponding to the cutout pattern 61B inthe configuration in FIG. 26 or FIG. 27. The plurality of the banded ITOpatterns 71A are mutually connected by connection parts 71C₁, 71C₂ and71C₃ and then are connected to the TFT 31T. The banded ITO pattern 71Acorresponds to the projection pattern 61A forming a zigzag shape (inFIG. 26 or FIG. 27) on the facing glass substrate 31B and then forms azigzag shape.

A Table 3 shown below shows the display characteristic in a case inwhich the length A and the width B as parameters in FIG. 29 arevariously changed in the liquid crystal display device 70 in FIG. 30. Itshould be noted that in this experiment, similarly to the fourthembodiment, the liquid crystal of Merck corporation as the liquidcrystal 31 is combined with the vertical molecule orientation film ofJSR corporation. The liquid crystal layer 33 has 4 μm. Also, in thepixel electrode structure 71, the pectinate ITO pattern 71B has a 3.5 μmand is periodically repeated at intervals of 6 μm.

TABLE 3 Occupied Rate Of pectinate Nonuniformity Improvement ratePattern Region In Of (B/(A + B)) Half Tone Response Speed 85 X ∘ (80%)75 x to Δ ∘ (75%) 65 Δ to ∘ ∘ (70%) 50 ∘ ∘ (60%) 35 ∘ Δ (25%) 25 ∘ x (upto 10%)

Referring to Table 3, when the length B of the pectinate pattern 71B ismore than 65% of a total width of the pectinate pattern 71B and thebanded ITO pattern 71A, nonuniformity occurs in the half tone displaymode. Accordingly, a preferable rate for the total width (A+B) of thepectinate pattern 71B is less than 65%. On the other hand, when thelength B of the pectinate pattern 71B is less than 35% of the totalwidth, an improvemed effect of the response characteristic is smaller.Accordingly, a preferable rate for the total width to the pectinatepattern 71B is more than 35%. Consequently, it is considered that adispersion of approximate 0.2 μm through 0.3 μm in a patterning of thepectinate pattern 71B emphasizes nonuniformity in the half tone displaymode.

FIG. 31A is a diagram showing a change of the transmittance and theresponse speed when a width W of the pectinate pattern 71B is variouslychanged in the liquid crystal display device 70 in FIG. 30. It should benoted that for a result in FIG. 31A, in the electrode 71 in FIG. 29, thewidth A of the banded ITO pattern 71A is 11 μm, the length B of thepectinate pattern 71B is 15 μm and the pectinate pattern 71B isperiodically formed at intervals of 6 μm.

Referring to FIG. 31A, when the width W of the pectinate pattern 71B is0 (zero), a response time of only the banded ITO pattern 71A isimproved. However, when the width W of the pectinate pattern 71B exceeds1.5 μm, the response time is dramatically improved. Then, when the widthW of the pectinate pattern 71B exceeds 3.5 μm, the response time isgradually increased. The response time is rapidly increased before andafter the width W of the pectinate pattern 71B is 4.5 μm. As shown inFIG. 31B, the liquid crystal molecules should be oriented toward adirection to properly display white, but the liquid crystal moleculestend to orient to another direction to display black, so that theorientations of the liquid crystal molecules are disordered. As aresult, the transmittance is degraded.

The result in FIG. 31A shows that a preferable width W of the pectinatepattern 71B is a range from 2.5 μm through 4.5 μm.

FIG. 32 is a diagram showing a relationship between an achievedtransmittance and a required time in the liquid crystal display device70 in FIG. 30. It should be noted that in FIG. 29, the width A of thebanded ITO pattern 71A is 11 μm, the length B of the pectinate pattern71B is 15 μm, a width of the gap G is 8 μm, the width W of the pectinatepattern 71B is 3.5 μm and the pectinate pattern 71B is periodicallyformed at intervals of 6 μm. And, the projection pattern 61A is notformed on the facing substrate 31B. In addition, FIG. 32 shows acharacteristic of the achieved transmittance and the required time ofthe conventional liquid crystal display device 10 in FIG. 1A and FIG.1B.

Referring to FIG. 32, compared with the conventional liquid crystaldisplay device 10, the required time especially in the half tone rangeis greatly shortened.

FIG. 33 is a diagram showing a relationship between an achievedtransmittance and a required time in the liquid crystal display device70 in FIG. 30. In this case in FIG. 33, projection patterns 61A similarto ones in FIG. 26 and FIG. 27 on the facing substrate 31B are formed.The relationship in this configuration is shown as a second variation inthe diagram in FIG. 33. And, the relationship in the liquid crystaldisplay 70 shown in FIG. 32 is shown as a first variation.

Referring to FIG. 33, in a case in which the projection pattern 61A isformed in the facing substrate 31B, especially when the transmittance iscloser to 0%, the required time is improved.

FIG. 34 is a diagram showing a relationship between a transmittance anda gradation in the first variation and the second variation in FIG. 33.It should be noted that in FIG. 34, a state in that the driving voltageis applied to the pixel electrode 71 is defined as 256 gradations.

Referring to FIG. 34, the transmittance of the liquid crystal displaydevice 70 is greatly improved by forming the projection pattern 61A onthe facing substrate 31B.

In the fifth embodiment, various patterns such as shown in FIG. 35Athrough FIG. 35C can be used as the pixel electrode 71.

In the fifth embodiment, the projection pattern 61A on the facingsubstrate 31B is not limited to a projection pattern such as a resistpattern or the like. The projection pattern 61A can be a cutout patternformed in the facing electrode 35 Also, the period of repeating thepectinate pattern 71B is not limited to the 6 μm interval. When theperiod is in a range greater than 2 μm and shorter than 15 μm, it ispossible to realize to effectively regulate the orientation of theliquid crystal molecules in the extended direction of the pectinatepattern.

[Sixth Embodiment]

Next, a method for fabricating a liquid crystal display device will nowbe described in a case in which a structural pattern in the liquidcrystal display device 30 described in the first embodiment; forexample, the structural pattern 34A in FIG. 8 is formed by a resistpattern.

Referring to FIG. 36A, a conducting film 81, which forms the scanelectrode 33 and the auxiliary capacitance electrode Cs, is uniformlyformed on the glass substrate 31A. Moreover, resist patterns R1 and R2,corresponding to a scan electrode pattern and an auxiliary capacitanceelectrode Cs, respectively, are formed on the conducting film 81.

In a next step in FIG. 36B, a patterning process is conducted for theconducting film 81 by using the resist pattern R1 and R2 as masks. Then,as shown as a plan view diagram in FIG. 36C, the scan electrode 33 andthe auxiliary capacitance electrode Cs are formed on the glass substrate31A. As a result of the patterning process in FIG. 36B, an electrode pad33A is formed at an end edge of the scan electrode 33 and an electrodepad CsA is formed at an edge of the auxiliary capacitance electrode Cs.

In a step in FIG. 36D, a gate insulating film 82, an amorphous siliconfilm 83 and an SiN film 84 are accumulated in sequence. And, a resistpattern R3 is formed on the SiN film 84 so as to cover over the TFT 31G.

Moreover in a step in FIG. 36E, the patterning process is conducted forthe SiN film 84 by using the resist pattern R3 as a mask. And, the theSiN channel protection film 84A is corresponded to a channel region ofthe TFT 31T and then is formed. FIG. 36F is a plan view diagram showinga structure formed in this method.

In a step in FIG. 36G, n+ type amorphous silicon film 85 and aconducting film 86 forming the signal electrode 32 are sequentiallyaccumulated and a resist pattern R4 corresponding to the signalelectrode 32 and a resist pattern R5 corresponding to the auxiliarycapacitance electrode Cs are formed on the conduction film 86. Theresist pattern R4 includes shapes corresponding to a source electrodepattern and a drain electrode pattern of the TFT 31T. By conducting thepatterning process for layers 83, 85 and 86 by the resist patterns R4and R5 as masks, as shown in FIG. 36H and FIG. 36I, a source electrodepattern 86S and a drain electrode pattern 86D of the TFT 31T are formedwith a channel layer pattern 83A, a source pattern 85S and a drainpattern 85D forming the TFT 31T. On the other hand, in the auxiliarycapacitance electrode region, a facing electrode pattern Cs′ forming acapacitor is simultaneously formed with the auxiliary capacitanceelectrode Cs. FIG. 36I is a plan view diagram showing a structure inthis method. In the patterning process in FIG. 36H, the signal electrode32 including the end of the pad electrode 32A is formed by thepatterning process for the conducting film 86.

In a step in FIG. 36J, a protection film 87 is uniformly accumulated onthe structure shown in FIG. 36H. Moreover, a resist pattern R6 formsresist opening parts RA and RB corresponding to the source electrodepattern 86S and the facing electrode pattern Cs′ facing the auxiliarycapacitance electrode Cs, respectively, on the protection film 87.

In a step in FIG. 36K, the patterning process is conducted for theprotection film 87 by the resist pattern R6 as a mask and then contactholes 87A and 87B are formed to the resist openings RA and RB,respectively, in the protection film 87. In addition, as shown in FIG.36L, simultaneously, a opening part 87A′ exposing the pad 33A in theprotection film 87 is formed at the electrode pad 33A. Subsequently, asshown in FIG. 36M, a contact hole 87A′ exposing the pad electrode CsA inthe protection film 87 is formed at the pad electrode 32A. FIG. 36N is aplan view diagram showing a structure obtained in this method.

In a step in FIG. 36O, on the structure in FIG. 36N, the ITO film 88 isuniformly accumulated so that the contact holes 87A and 87B contact thesource region 86S and the facing electrode Cs facing the auxiliarycapacitance electrode Cs, respectively. Subsequently, a resist patternR7 corresponding to a pixel electrode 34 to be formed is formed on theITO film 88. In a step in FIG. 36P, the patterning process is conductedfor the ITO film 88 by the resist pattern R7 as a mask, so that thepixel electrode 34 is formed.

Simultaneously, as shown in FIG. 36Q and FIG. 36R, the electrode pads33A and 32A are formed so that the ITO contact pads 88A and 88B contactthe electrode pads 33A and 32A at the contact holes 87A′ and 87B′,respectively.

FIG. 36S is a plan view diagram showing the substrate 31A obtained inthis method.

In a step in FIG. 36T in the sixth embodiment, a resist film isuniformly covered over an entire surface of the structure shown in FIG.36S. And, by an exposing process and a developing process, a structuralpattern 34X, which includes micro branches corresponding to themicro-cutout patterns 34A previously described in FIG. 8, is formed by ashape of a resist pattern. Then, a liquid crystal display device 80corresponding to the liquid crystal display device 30 is obtained.

In order to effectively regulate the orientation direction of the liquidcrystal molecules for the structural pattern 34X, a width of each microbranch is required to be less than 6 μm. For example, the resist filmcan be in a range of 600 nm through 800 nm by adjusting a coefficient ofviscosity of a resist SC-1811 of Shipley Far East Corporation.Preferably, the resist film can be approximately 700 nm in thickness. Itis possible to maintain a 100 nm to 700 nm thickness of the resist filmas the resist pattern after the exposing process and the developingprocess, by a uniformly approximate 700 nm thickness of the resist film.In this case, in order to suppress a decrease of a film thickness at atop edge of each branch in the developing process, a gh line stepper isused in the exposing process and preferably an exposure dose, whichgenerally is set to be more than double of an exposure threshold, is setto be approximate 1.5 times as much as the exposure threshold, a socalled “underexposure”.

After the exposing process and the developing process, an ashing processand a removing process are conducted to a surface layer of the resistpattern 34X so that the thickness of the resist pattern 34X isapproximate 300 nm. For example, in the ashing process, a reactiveplasma etching device is used while O₂ is supplied at 400SCCM flow by apressure under 30.0 Pa and a 600 W plasma power.

After the ashing process, a thermosetting process is conducted for theresist pattern 34X. That is, the thermosetting process begins at atemperature of less than 140° C., preferably approximately at 130° C.The thermosetting process gradually rises up to 140° C.–270° C. andpreferably heats and hardens the resist pattern 34X at a hightemperature and high humidity for more than 10 minutes. In this method,even if the micro-branches of the resist pattern 34X are 6 μm in width,it is possible to harden the resist pattern 34X without deterioratingthe shapes of the micro-branches.

Moreover, in the same method, as shown in FIG. 37, it is possible toform a resist pattern 34Y having micro-branches having sharpened edges.Furthermore, according to the sixth embodiment, it is possible to formthe directional pattern 24E or 24E′ previously described in FIG. 21 orFIG. 23. A configuration in FIG. 37 approximately corresponds to theconfiguration of the liquid crystal display device 50.

In the sixth embodiment, as the resist film, various polyimide resins,novolak resins or acrylic resins can be used.

[Seven Embodiment]

A configuration of a liquid crystal display device 90 will now bedescribed according to a seventh embodiment.

In the liquid crystal display device 90 according to the seventhembodiment, a thickness of each branch of the pattern 34X in FIG. 36 orthe pattern 34Y in FIG. 37 is thinner toward the end edge.

FIG. 38A and FIG. 38B are diagrams showing a principle of the seventhembodiment according to the present invention.

Referring to FIG. 38A and FIG. 38B, the liquid crystal display device 90is configured based on the liquid crystal display device 10 in FIG. 1Aand FIG. 1B, and the liquid crystal layer 12 is maintained between theglass substrate 11A where the projection pattern 13A is formed and theglass substrate 11B where the projection pattern 13B is formed. Microdirectional patterns 13 a, which have sharpened edges laterally from theprojection pattern 13A, are extended similarly to the directionalpattern 24E in FIG. 21 or the directional pattern 24E′.

In this case, as shown in a sectional view diagram in FIG. 38B, not onlya width but also a height and a thickness of the micro directionalpattern 13 a are gradually decreased toward the edge. As a result,slopes facing each other are formed by a pair of the micro directionalpatterns 13 a facing each other. The projection pattern 13B on glasssubstrate 11B is formed so as to face toward the micro directionalpattern 13 a and then a pre-tilt is applied to the liquid crystalmolecules in the liquid crystal layer 12. As a result, when the drivingelectric field is applied to the liquid crystal layer 12, the liquidcrystal molecules are rapidly tilted to orient toward in an approximatehorizontal direction. In this case, the micro directional pattern 13 ais periodically repeated to form typically at intervals of a few μm.Thus, as described in previous embodiments, the tilt direction of theliquid crystal molecules is regulated in the extended direction of themicro directional pattern 13 a.

For example, the micro directional pattern 13 a forming a slope can beformed by exposing a positive resist by using a photo mask shown in FIG.39.

As a typical example, a spin coating process, in which a positive resistS1808 manufactured by Shipley Far East corporation is 0.1 μm to 3 μm inthickness, typically approximate 1.5 μm, is conducted so as to cover thepixel electrode on the glass substrate 13A.

Subsequently, the resist film masked by the photo mask in FIG. 39 isexposed to ultraviolet rays and then a developing process, a rinsingprocess and a baking process are conducted. Consequently, as shown inFIG. 38A and FIG. 38B, it is possible to form the projection pattern 13Aso that the micro directional pattern 13 a is laterally extended.

FIG. 40 is a diagram showing a result of simulating an operation of theliquid crystal display device 90 configured in this method. In FIG. 40,a right diagram shows a case of the present invention in that the microdirectional pattern 13 a is provided and a left diagram shows a case ofthe conventional configuration in that the micro directional pattern 13a is not provided. In FIG. 40, a required time to achieve to a givencontrast, which is variously defined, is shown. According to the presentinvention, as a result of providing the micro directional pattern 13 a,the required time is decreased in a vicinity of the projection pattern13A.

Table 4 shows a comparison of the conventional liquid crystal displaydevice 10 in FIG. 1A and FIG. 1B and the liquid crystal display device90 in the seventh embodiment in FIG. 38A and FIG. 38B where an appliedvoltage is 2.5V or 3.0V.

TABLE 4 Applied Conventional Present Voltage Method Invention 2.5 V 520ms 238 ms 3.0 V 166 ms 117 ms

Table 4 explicitly shows that the micro directional pattern 13 acontributes to reduce the response time.

In the seventh embodiment, since the micro directional pattern 13 a isinclined, it is not required for the micro directional pattern 13 a tobe sharpened. For example, a pattern 13 a′ having a uniform width shownin FIG. 41A or a pattern 13 a″ in FIG. 13B which width is increasedtoward the edge can also obtain a similar effect.

[Eighth Embodiment]

FIG. 42 is a diagram showing a liquid crystal display device 100according to an eighth embodiment of the present invention.

The liquid crystal display device 100 in FIG. 42 is configured based onthe configuration of the liquid crystal display device 30 previouslydescribed. Thus, in FIG. 42, elements that are the same as the ones inprevious figures are indicated by the same reference numerals and theexplanation thereof will be omitted.

Referring to FIG. 42, on the pixel electrode 34, a plurality ofdirectional patterns 101A similar to the directional pattern 24Adescribed in FIG. 16 is formed at column intervals WG and at rowintervals HG in a matrix in a common direction.

FIG. 43 is a diagram showing the directional pattern 101A according toan eighth embodiment of the present invention.

Referring to FIG. 43, the directional pattern 101A is a wedge shape witha width W and a height H and a cutout portion with a width SW and aheight SH is formed at a bottom of the directional pattern 101A. Thedirectional pattern 101A can be a resist pattern formed in the pixelelectrode 34 or a cutout pattern formed in the pixel electrode 34. Inthis case, the width W is 8 μm, the width SW is 4 μm, the height H is 30μm and the height SH is 5 μm to 20 μm, and the directional pattern 101Ais repeated to be arranged at intervals of 2 μm width WG and atintervals of 0 μm height HG on the pixel electrode 34.

By forming the directional pattern 101A, the liquid crystal molecules inthe liquid crystal layer 31 are regulated to orient in a directiondefined by the directional pattern 101A, as previously described.Consequently, when the driving voltage is applied to the liquid crystallayer 31, the liquid crystal molecules are quickly tilted. Thus, atransition to a nine-layer state is occurred at a high speed.

FIG. 44 is a diagram showing a first variation of the liquid crystaldisplay device 100 in FIG. 42, according to the eighth embodiment of thepresent invention. In FIG. 44, the pixel electrode 34 are sectioned intoa domain A and a domain B in the liquid crystal display device 100 inFIG. 42, and the orientation direction of the directional pattern 101Ais different in each of the domain A and the domain B as shown byarrows. According to the first variation of the eighth embodiment, it ispossible to improve a characteristic of a visible angle in the liquidcrystal display device 100.

FIG. 45 is a diagram showing a second variation of the liquid crystaldisplay device 100 in FIG. 42, according to the eighth embodiment of thepresent invention. In FIG. 45, in the liquid crystal display device 100in FIG. 42, the pixel electrode 34 is sectioned into domains A, B, C andD similarly to the configuration in FIG. 15 and the orientationdirection of the directional pattern 101A is different in each ofdomains A, B, C and D as shown by arrows. According to the secondvariation of the eighth embodiment, it is possible to further improvethe characteristic of the visible angle in the liquid crystal displaydevice 100.

FIG. 46 is a diagram showing a third variation of the liquid crystaldisplay device 100 in FIG. 44, according to the eighth embodiment of thepresent invention. In FIG. 46, in the liquid crystal display device 100in FIG. 42, a structural pattern 102 configured by a resist pattern or acutout pattern is formed similarly to the projection pattern 13A in theliquid crystal display device 10 in FIG. 1A and FIG. 1B, at a borderbetween the domain A and the domain B.

According to the third variation of the eighth embodiment, it ispossible to further improve regulating the orientation of the liquidcrystal molecules in directions, which are indicated by arrows, of thedirectional pattern 101A by the structural pattern 102.

FIG. 47 is a diagram showing a fourth variation of the liquid crystaldisplay device 100 in FIG. 45, according to the eighth embodiment of thepresent invention. In FIG. 47, a lattice shaped structural pattern 102Bconfigured by a lattice shaped resist pattern or a lattice shaped cutoutpattern is formed in the configuration of the liquid crystal displaydevice 100.

According to the fourth variation of the eighth embodiment, since thelattice shaped pattern 102B is formed, it is possible to further improveregulating the orientation of the liquid crystal molecules in directionsdirected by the directional pattern 101A and indicated by arrows.

FIG. 48 is a diagram showing a fifth variation of the directionalpattern 101A. In FIG. 48, another directional pattern 101B based on thedirectional pattern 101A is shown.

Referring to FIG. 48, the directional pattern 101B is an inverted Tpattern having a width W and a height H, in which a bottom member hasthe width W and a height SH and a projecting member has a width SW andprojects from the bottom member.

As a typical example, the width W is set from 5 μm to 8 μm, the heightis set from 10 μm to 30 μm, the width SW of the projecting member is setfrom 2 μm to 3 μm, and the height SH of the bottom member is set from 3μm to 5 μm. The directional pattern 101A is arranged at row intervals HGof 2 μm and at column intervals WG of 2 μm on the pixel electrode 34 inthe configuration in FIG. 42.

FIG. 49 shows diagrams of various directional patterns, instead of thedirectional pattern 101A or 101B.

These various directional patterns in

FIG. 49 generally have line symmetric shapes that are not rotationsymmetries. As previously described, the various directional patternscan be resist patterns formed on the pixel electrode 34 or cutoutpatterns formed in the pixel electrode 34.

FIG. 50A and FIG. 50B are diagrams showing arrangement variations of thedirectional pattern according to the eighth embodiment of the presentinvention.

In FIG. 50A, right triangle shaped patterns are arranged to form a crossshape where a top edge of each directional pattern directs anorientation. A set of the directional patterns regulates the orientationof the liquid crystal molecules. In this case, the right triangle shapedpatterns are not the directional patterns having rotation symmetries.However, it is possible to realize predetermined effects by forming theset of non-directional patterns such as the right triangle shapedpatterns.

On the other hand, in a configuration shown in FIG. 50B, a plurality ofdirectional patterns having isosceles triangles are arranged to haverotation symmetry at a center. It can be also realized to regulate theorientation of the liquid crystal molecules in the above configuration.

When the directional patterns 101A in FIG. 43 are formed on the pixelelectrode 31 so as to arrange in a lattice shape, the directionalpattern 101A can be alternately arranged as shown in FIG. 51.

Also, if necessary, it is also possible to arrange the directionalpatterns 101A in a concentric circle or spiral as shown in FIG. 52.

[Ninth Embodiment]

FIG. 53A is a sectional view diagram showing a liquid crystal displaydevice 110 according to a ninth embodiment of the present invention andFIG. 53B is a plan view diagram showing a liquid crystal display device110 according to the ninth embodiment of the present invention. In FIG.53A, a sectional view of the liquid crystal display device 110 is shownat a line A to A′ in FIG. 53B.

Referring to FIG. 53A, in the liquid crystal display device 110, theliquid crystal layer 113 is clamped between a glass substrate 112Acarrying a pixel electrode 112A and a glass substrate 111B, and aprojection pattern 114A is formed with lattice shapes on the pixelelectrode 112A and a projection pattern 114B is formed with latticeshapes on the pixel electrode 112B.

On the projection pattern 114A (hereinafter, called lattice shapedpattern 114A), a localized pattern 114 a forming a slope as shown inFIG. 53A and FIG. 53B is formed at a cross point of each lattice shape.Similarly, on the projection pattern 114B (hereinafter, called latticeshaped pattern 114B), a localized pattern 114 b forming a slope isformed at a cross point of each lattice shape.

Moreover, a vertical molecule orientation film 115A is formed on theglass substrate 111A so as to cover the lattice shaped pattern 114A, andalso a vertical molecule orientation film 115B is formed on the glasssubstrate 111B so as to cover the lattice shaped pattern 114B. Thevertical molecule orientation films 115A and 115B are adjacent to theliquid crystal layer 113, and the vertical molecule orientation films115A and 115B allow the liquid crystal molecules in the liquid crystallayer 113 to orient in a direction that is vertical to the liquidcrystal layer 113. And also, a polarizer 115A outside of the glasssubstrate 111A and an analyzer 115B outside of the glass substrate 111Bare formed in a crossed Nicol state, respectively. In FIG. 53B,directions of absorbent axes of the polarizer 115A and the analyzer 115Bare shown, respectively.

In the liquid crystal display device 110, the pre-tilt angle, similar toFIG. 3A and FIG. 3B previously described, is given to the crystalmolecules in the liquid crystal layer 113 by the lattice shaped patterns114A and 114B and by slopes formed by the localized patterns 113 a and113 b. As a result, when the driving electric field is applied tobetween the vertical molecule orientation films 115A and 115B, theliquid crystal molecules quickly fall down. Therefore, the operationspeed of the liquid crystal display device 110 is improved.

FIG. 54 is a diagram showing the orientation of the liquid crystalmolecules 113A in the liquid crystal layer 113 in the driving state ofthe liquid crystal display device 110, according to the ninth embodimentof the present invention.

Referring to FIG. 54, directions of absorbent axes of the polalizer 116Aand the analyzer 116B are set so as to correspond to an extendeddirection of the lattice shaped patterns 114A and 114B. On the rightabove the lattice shaped patterns 114A and 114B, a single dark lineoccurs, similarly to the case in FIG. 9. However, double dark lines donot occur at both sides of the lattice shaped pattern 114A or 114B.Therefore, it is possible to eliminate the problems, described in FIG.2, related to the occurrences of the double dark lines and thedeterioration of the transmittance caused by the occurrences of thedouble dark lines.

Next, a method for fabricating the liquid crystal display device 110shown in FIG. 53A and FIG. 53B, will now be described with reference toFIG. 55A through FIG. 55D.

Referring to FIG. 53A, a resist film 114, which is typically a positivetype resist S1808 manufactured by Shipley Far East Corporation, isformed on the glass substrate 111A so as to cover the pixel electrode112A. When a pre-baking process is conducted at 90° C. for 20 minutes,an exposing process is conducted by using a mask M1 and then adeveloping process is conducted by, for example, liquid developer MF319manufactured by Shipley Far East Corporation or the like. Then, thelattice shaped pattern 114A is formed as shown in FIG. 53B. In a step inFIG. 53B, a post-baking process is conducted to the lattice shapedpattern 114 at 120° C. for 40 minutes and the post-baking process isfurther conducted at 200° C. for 40 minutes.

In a step in FIG. 55C, a resist film 114′ configured by the localizedpattern 114 a is formed on the glass substrate 111A so as to cover thelattice shaped pattern 114A. Subsequently, the exposing process and thedeveloping process are conducted by using a mask M2. As shown in FIG.55D, the localized pattern 114 a is formed at a cross point of eachlattice of the lattice shaped pattern 114A. That is, the localizedpattern 114 a is formed so that typically, one side is 45 μm and aheight is 0.3 μm. On the other hand, for example, a width of the latticeshaped pattern 114A itself is 5 μm.

In a step in FIG. 55D, for example, a vertical orientation film JALS684manufactured by JSR Corporation is formed as the molecule orientationfilm 115A so as to cover the lattice shaped pattern 114A and thelocalized pattern 114 a.

Similarly, the lattice shaped pattern 114B and the localized pattern 114b are formed on the glass substrate 111B.

When the glass substrates 111A and 111B are combined together and theliquid crystal display device 110 is formed, the lattice shaped patterns114A and 114B are formed so as to be spaced 20 μm between the latticeshaped patterns 114A and 114B.

FIG. 56 is a diagram showing a first variation of the liquid crystaldisplay device 110 according to the ninth embodiment of the presentinvention.

In FIG. 56, instead of the localized patterns 114 a and 114 b, alocalized pattern 114 c and 114 d having projections extending at 45° toan extended direction of the lattice shaped pattern 114A and 114B.

According to the first variation in FIG. 56, it is possible to realize adesired pre-tilt direction of the liquid crystal molecules in anintermediate region between the lattice shaped patterns 114A and 114B,in which region pre-tilt effects of the lattice shaped patterns 114A and114B are not directly given to the intermediate region.

On the contrary, FIG. 57 is a diagram showing a second variation of theliquid crystal display device 110 according to the ninth embodiment ofthe present invention.

In FIG. 57, instead of the localized patterns 114 a and 114 b, alocalized pattern 114 e and 114 f having projections extending in anextended direction of the lattice shaped pattern 114A and 114B.

According to the second variation in FIG. 57, it is possible to furtherreinforce the pre-tilt effects of the lattice shaped patterns 114A and114B by the localized patterns 114 e and 114 f.

FIG. 58 is a diagram showing a third variation of the liquid crystaldisplay device 110 according to the ninth embodiment of the presentinvention.

In FIG. 58, the first variation and the second variation are joined inthe third variation. That is, a localized pattern 114 g is formed ateach cross point of the lattice shaped pattern 114A and a localizedpattern 114 h is formed at each cross point of the lattice shapedpattern 114B.

And FIG. 59 is a diagram showing a fourth variation of the liquidcrystal display device 110 according to the ninth embodiment of thepresent invention.

In FIG. 59, the first variation and the second variation are superposedin the third variation. That is, the localized pattern 114 e is formedon the localized pattern 114 c and the localized pattern 114 f is formedon the localized pattern 114 d.

According to the fourth variation in FIG. 59, especially, it is possibleto realize steep slopes of the localized patterns 114 e and 114 f.Therefore, the pre-tilt effect of the liquid crystal molecules can beenhanced.

The variations shown in FIG. 53 through FIG. 59 can be applied to anyembodiments previously described and can contribute to improve theoperation speed of the liquid crystal display device.

According to the present invention, the structural pattern is to form anelectric field periodically changing in the second direction. Thus, thestructural pattern may be a convex pattern that is formed on the firstelectrode and is made up of an insulating material or a conductingmaterial, or a concave pattern such as a cutout pattern or the likeformed on the first electrode. Also, in the present invention, aplurality of pixel electrodes is preferably used as the first electrode.However, in this case, each of the plurality of pixel electrodes issectioned into a plurality of domains. The structural pattern is formedin each of the plurality of domains so that the first direction in onedomain crosses the first direction in other domains adjacent to sides ofthe one domain at 90° angle. The visibility angle, which is superior byapplying the vertical orientation mode, can be more improved. On thefirst substrate, thin film transistors, which correspond to a pluralityof pixel electrodes, respectively, and drives the pixel electrodes, areformed. Then, by applying a active matrix driving method, the liquidcrystal display device according to the present invention can optimizeits superior response characteristic.

On at least one of the first substrate and the second substrate, anotherstructural pattern different from the structural pattern can be formedso as to cross the first direction and be repeat in a differentdirection from the second direction at intervals of substantially agreater period than the repeat period which the structural pattern isrepeated in the second direction at. By forming another structuralpattern, it is possible to uniquely determine a tilt direction of theliquid crystal molecules when the voltage is applied. And it is possibleto improve an effect of regulating the tilt direction of the liquidcrystal molecule by the micro patterns. As a result, the response speedof the liquid crystal display device is improved. Preferably, anotherstructural pattern has a higher height than the structural pattern.

When the structural pattern is formed by a plurality of micro patternsthat extend in the first direction and are repeated in the seconddirection at a first period, another structural pattern is formed by afirst rough structural pattern formed on the first substrate andextending in a third direction crossing the first direction, and asecond rough structural pattern formed on the second substrate andextending in a fourth direction vertically crossing the seconddirection. Preferably, the first rough structural pattern is repeated inthe fourth direction at intervals of substantially a greater period thanthe first period and the second rough pattern is repeated in the thirddirection at intervals of substantially a greater period than the firstperiod. In order to maximally the response speed improved by anotherstructural pattern, it is preferably that each of the first roughstructural pattern and the second rough structural pattern has a widerwidth than the micro pattern. It is preferable that the third directionvertically crosses the first direction, or the third direction crossesthe first direction at 45° angle.

When the structural pattern is formed by a plurality of micro patternsthat extend in the first direction with a first width and are repeatedin the second direction at a first period, another structural patterncan be formed by a first lattice shaped pattern and a second latticeshaped pattern. The first lattice shaped pattern is formed on the firstsubstrate so as to extend in a third direction obliquely crossing thefirst direction and the second direction and a fourth directionvertically crossing the third direction. The second lattice shapedpattern is formed on the second substrate at a position displaced fromthe first lattice shaped pattern so as to extend in the third directionand in the fourth direction. In this case, the first lattice shapedpattern and the second lattice shaped pattern are repeated at intervalsof greater periods than the first period, respectively. In thisconfiguration, it is preferable that each of the first lattice shapedpattern and the second lattice shaped pattern has a wider width than themicro pattern. In addition, it is preferable that the third directioncrosses the first direction at 45° angle. In this case, the firstlattice shaped pattern is sectioned into a first, a second, a third anda fourth domains on the first substrate and the micro pattern is formedso that the first direction in one of the first, the second, the thirdand the fourth domains and the first direction in each of other domainsadjacent to the one domain form a 90° angle. Therefore, it is possibleto optimize the characteristic of the visible angle.

Another structure pattern described above can be a convex pattern or aconcave pattern.

Also, according to the present invention, it is preferable that each ofpatterns forming the structural pattern is directional and directs atleast one direction in the first direction. For example, it ispreferable that each of the plurality of patterns has approximately atriangle shape and is formed so that a vertex of the triangle directsthe direction. Alternatively, it is preferable that each of theplurality of patterns has a rhombus shape having a first vertex and asecond vertex opposing each other in that said first vertex directs saidfirst direction as one direction and said second vertex directs saidsecond direction as an opposed direction. By using the directionalpattern as the structural pattern, when the liquid crystal molecules inthe liquid crystal layer tilt in the driving state, a tilt direction isuniquely determined in the first direction. As a result, the responsespeed of the liquid crystal display device is improved. Also, in a casein which an optical hardened material of the optical hardened composite,similar effect can be achieved. It is preferable that each of theplurality of the directional patterns has a maximum width less than 10μm.

The present invention is not limited to the specifically disclosedembodiments, variations and modifications, and other variations andmodifications may be made without departing from the scope of thepresent invention.

The present application is based on Japanese Priority Application No.2000-295266 filed on Sep. 27, 2000, the entire contents of which arehereby incorporated by reference.

1. A method for fabricating a liquid crystal display device including aliquid crystal layer clamped between a first substrate and a secondsubstrate, said method comprising the steps of: (a) forming a pixelelectrode pattern on said first substrate; (b) painting a resist film onsaid pixel electrode pattern; (c) exposing and developing said resistfilm and forming a resist pattern having a shape on said pixel electrodepattern in which multiple branches extend outwardly from both sides of amain stem connecting among the multiple braches; (d) conducting anashing process for said resist pattern; and (e) conducting athermosetting process for said resist pattern; so that liquid crystalmolecules in said liquid crystal layer orient approximately in verticalto a surface of said liquid crystal layer in a non-driving state inwhich a driving electric field is not applied to said liquid crystallayer, and said liquid crystal molecules orient approximately inparallel to said surface of said liquid crystal layer in a driving statein which the driving electric field is applied to said liquid crystallayer.
 2. The method as claimed in claim 1, wherein said step (c)includes the step of exposing said resist film at less than doubleexposure amount of an exposure threshold for said resist film.
 3. Themethod as claimed in claim 1, wherein said step (b) includes the step offorming said resist film having such a thickness that a thickness ofsaid resist pattern is in a range from 100 nm to 700 nm after saidashing process.
 4. The method as claimed in claim 1, wherein said step(b) includes the step of adjusting a viscosity of said resist film sothat a thickness of said resist film is in a range from 600 nm to 800nm.
 5. The method as claimed in claim 1, wherein said step (e) includesthe step of starting the thermosetting process at a temperature lowerthan 140° C. and gradually rising the temperature up to a thermosettingtemperature that is lower than 270° C.